1. Field of the Invention
The present invention relates to a white-board marker for writing on a white board, a writing-utensil-type paint marker for applying paint to the surface of metal or plastic material, a nail marker for applying manicure solution to nails, and a marker for applying liquid to a specified surface.
The present invention more particularly relates to an improvement of a marker storing a slidable slide plug in an ink reservoir.
2. Description of the Related Art
The above markers, unlike a writing utensil for writing characters on paper, are a kind of writing utensil configured to apply liquid in a relatively wide path. The structure of conventional markers is the same as that of a writing utensil for writing characters except that a pen element is thick. These markers use a pen element made of hardened fibers such as felt which is a so called felt tip.
These markers, however, should reserve a lot of ink because they consume ink in large quantities (hereafter referred to as ink and representing paint, manicure solution, and other liquid) unlike a writing utensil for writing characters.
For the writing utensil for writing characters (e.g. a felt-tip pen), the ink reservoir is filled with fibers such as cotton. Ink is held in reserve by making the fibers hold ink by means of capillarity, and writing is executed by absorbing the ink by the capillarity force of the felt tip.
Though this type of pen has a simple structure, it can reserve only a little ink. Therefore, this structure cannot be used for the above markers. A structure storing a slide plug in the ink reservoir is suitable to reserve a lot of ink. For this structure, a slidable slide plug maintaining liquid-tightness is inserted into a cylindrical ink reservoir. The ink reservoir is filled with liquid ink and the above slide plug separates the liquid ink from an air portion. As the ink is consumed or it is expanded or contracted due to temperature change, the slide plug slides to keep the pressure of the ink in the ink reservoir equal to the atmospheric pressure.
However, when the ink reservoir equipped with the above slide plug is used for markers, trouble occurs in that ink is inadequately absorbed from the pen element.
The first reason for this lies in the fact that the marker ink used for quick-drying ink, paint, and manicure solution has inadequate capillarity force because it has a comparatively high viscosity and contains an organic solvent. Therefore, the felt tip serving as a pen element has an inadequate ink-absorbing force. For aqueous ink used for a felt tip pen for writing characters, for example, the felt tip produces the absorbing differential pressure of 300 mmAq or more as the water head pressure. However, alcohol-based quick-drying ink used for white board markers produces the absorbing differential pressure of only approx. 100 mmAq under the same condition. When the above slide plug slides, it has a certain degree of sliding resistance. In addition, for an extremely small sliding resistance of the slide plug, ink drips from the pen element due to the water head pressure of the ink in the ink reservoir when the white board marker with the pen element turned downward is left as it is. Therefore, it is necessary to increase the sliding resistance of the slide plug to a certain degree. The slide plug is moved by the differential pressure produced when the above pen element or the felt tip absorbs ink. However, because the marker ink has inadequate capillarity force, ink may not completely be absorbed due to the sliding resistance of the slide plug.
The second reason lies in the fact that surfaces to which ink is applied by these markers have no water absorbing property because they are made of plastics or metal. Therefore, to completely apply ink to these surfaces, it is necessary for the marker felt tip to adequately contain ink. However, for markers which absorb ink by the capillarity force of the felt tip, like the conventional writing utensils, the felt tip cannot adequately contain ink.
Because of the above reasons, the amount of ink to be applied is limited for conventional markers. Therefore, no deep handwriting can be obtained by, for example, a white-board marker.
The present invention solves the above problems and it is an object of this invention to provide a marker having an ink reservoir storing a slide plug and capable of adequately supplying ink to a pen element.